HARVESTING AND PREPARATION 59 



(b) Changes in the Interior of the Bean. What is 

 the relation between the comparatively simple fer- 

 mentation of the pulp and the changes in the interior 

 of the bean ? This important question has not yet been 

 answered, although a number of attempts have been 

 made. 



As far as is known, the living ferments (micro- 

 organisms) do not penetrate the skin of the bean, so 

 that any fermentation which takes place must be 

 promoted by unorganised ferments (or enzymes). Mr. 

 H. C. Brill* found raffinase, invertase, casease and 

 protease in the pulp ; oxidase, raffinase, casease and 

 emulsinlike enzymes in the fresh bean ; and all these 

 six, together with diastase, in the fermented bean. Dr. 

 Fickendey says : " The object of fermentation is, in 

 the main, to kill the germ of the bean in such a manner 

 that the efficiency of the unorganised ferment is in no 

 way impaired." 



From my own observations I believe that forastero 

 beans are killed at 47 degrees C. (which is commonly 

 reached when they have been fermenting 60 hours), 

 for a remarkable change takes place at this temperature 

 and time. Whilst the micro-organisms remain outside, 

 the juice of the pulp appears to penetrate not only the 

 skin, but the flesh of the bean, and the brilliant violet 

 in the isolated pigment cells becomes diffused more 

 or less evenly throughout the entire bean, including 

 the " germ." It is certain that the bean absorbs liquid 

 from the outside, for it becomes so plump that its skin 

 is stretched to the utmost. The following changes occur : 



(1) Taste. An astringent colourless substance (a tannin or a body 

 possessing many properties of a tannin) changes to a tasteless 

 brown substance. The bean begins to taste less astringent as 

 the "tannin" is destroyed. With white (criollo) beans this 



change is sufficiently advanced in two days, but with purple 

 (forastero) beans it may take seven days. 



(2) Colour. The change in the tannin results in the white (criollo 

 beans becoming brown and the purple (forastero) beans be- 



* Philippine Journal of Science, iqi 7 



